Biosensor for multi-analyte characterization

ABSTRACT

Embodiments of the present invention are directed to a semiconductor device. A non-limiting example of the semiconductor device includes a semiconductor substrate. The semiconductor device also includes a plurality of metal nanopillars formed on the substrate. The semiconductor device also includes an amperometric sensor associated with one of the plurality of nanopillars, wherein the amperometric sensor is selective to an enzyme-active neurotransmitter. The semiconductor device also includes a resistivity sensor associated with a pair of nanopillars, wherein the resistivity sensor is selective to an analyte.

DOMESTIC PRIORITY

This application is a divisional of U.S. application Ser. No.15/671,938, titled “Biosensor for Multi-Analyte Characterization” filedAug. 8, 2017, the contents of which are incorporated by reference hereinin its entirety.

BACKGROUND

The present invention generally relates to fabrication methods andresulting structures for biosensors. More specifically, the presentinvention relates to biosensors for multi-analyte characterization.

Biosensors can be useful for the detection and characterization ofbiomolecules. There exist a variety of different types of bio sensors,including calorimetric biosensors, potentiometric biosensors, acousticwave biosensors, amperometric biosensors, and optical biosensors.Biosensors can be tailored to sense a specific analyte for specificapplications. For instance, specific neurotransmitters, such asdopamine, can be detected in vivo for the study of neurologicaldisorders.

Many biological processes, disorders, and diseases simultaneouslyimplicate actions and interactions of a plurality of biomolecules.Studies of the interplay and relationships between such molecules canrequire sensing of multiple analytes. Moreover, the location of suchbiomolecules can be an important factor in biological function. Forexample, in the case of neurotransmitters, neurotransmitters can travelacross a short distance of a synapse and the locations of suchneurotransmitters can play an important role in understandingneurological processes. In addition, a neuron can have a length of fromabout 10 to 100 microns and, depending on biological state, differentbiomolecules can be present at different locations along theneurotransmitter. In such applications, multi-analyte sensing capabilityand biosensors with nanoscale resolution can provide valuableinformation.

SUMMARY

Embodiments of the present invention are directed to a method forfabricating a semiconductor device. A non-limiting example of the methodincludes forming a plurality of nanopillars on a substrate, theplurality of nanopillars including a first nanopillar and a pair ofadjacent nanopillars. The method also includes forming an insulatinglayer on the plurality of nanopillars to generate a plurality of linednanopillars. The method also includes removing the insulating layersfrom upper portions of the pair of adjacent nanopillars to generateexposed adjacent nanopillar portions. The method also includes forming aresistivity sensor on the exposed adjacent nanopillar portions. Themethod also includes removing the insulating layer from the firstnanopillar to generate an exposed first nanopillar portion. The methodalso includes forming an amperometric sensor on the exposed firstnanopillar portion. Such embodiments of the invention can advantageouslyform a semiconductor device with multi-analyte sensing capability thatcan provide nanoscale resolution.

Embodiments of the present invention are directed to a semiconductordevice. A non-limiting example of the semiconductor device includes asemiconductor substrate. The semiconductor device also includes aplurality of metal nanopillars formed on the substrate. Thesemiconductor device also includes an amperometric sensor associatedwith one of the plurality of nanopillars, wherein the amperometricsensor is selective to an enzyme-active neurotransmitter. Thesemiconductor device also includes a resistivity sensor associated witha pair of nanopillars, wherein the resistivity sensor is selective to ananalyte. Such embodiments of the invention can advantageously sensemultiple biological analytes simultaneously and in real-time.

Embodiments of the present invention are directed to a multi-analytebiosensor. A non-limiting example of the biosensor includes a substrate.The biosensor also includes a first nanopillar including a baseconnected to the substrate. The biosensor also includes a secondnanopillar including a base connected to the substrate, wherein thesecond nanopillar is adjacent to the first nanopillar. The biosensoralso includes an imprinted polymer physically contacting at least aportion of the first nanopillar and at least a portion of the secondnanopillar, wherein the imprinted polymer includes a conductive porouspolymer including a plurality of cavities with affinity to a firstanalyte. The biosensor also includes a third nanopillar including a baseconnected to the substrate, wherein the third nanopillar is lined withan amperometric sensor polymer including a plurality of binding siteswith affinity to a second analyte. Such embodiments can advantageouslydetect both enzymatic and non-enzymatic biological analytes in abiological tissue sample.

Embodiments of the present invention are directed to a multi-analytebiosensor. A non-limiting example of the biosensor includes asemiconductor substrate. The multi-analyte biosensor also includes afirst sensing region including a first plurality of nanopillarsconnected to a first conductive polymer selective to a firstbiomolecule, wherein the first sensing region is connected to thesemiconductor substrate. The multi-analyte biosensor also includes asecond sensing region including a second plurality of nanopillarsconnected to a second conductive polymer selective to a secondbiomolecule, wherein the second sensing region is connected to thesemiconductor substrate and wherein the second biomolecule is differentthan the first biomolecule. The multi-analyte biosensor also includes aninterface layer connecting the semiconductor substrate to a processor.The multi-analyte biosensor also includes a communications interface.Such embodiments can advantageously sense multiple analytes and theirpositional information in real time and provide concentration andposition information to a user.

Embodiments of the invention are directed to a computer-implementedmethod of multi-analyte detection. A non-limiting example of the methodincludes receiving, to a processor, a signal from a multi-analyte sensorin contact with a biological tissue, wherein the multi-analyte sensorincludes a resistivity sensor and an amperometric sensor. The methodalso includes determining, by the processor, a resistivity value fromthe resistivity sensor. The method also includes generating, by theprocessor, a concentration of a first analyte based at least in partupon the resistivity value. The method also includes determining, by theprocessor, an electrical current from the amperometric sensor. Themethod also includes generating, by the processor, a concentration of asecond analyte based at least in part upon the electrical current. Suchembodiments can advantageously determine the concentration of multipleanalytes at nanoscale resolution.

Additional technical features and benefits are realized through thetechniques of the present invention. Embodiments and aspects of theinvention are described in detail herein and are considered a part ofthe claimed subject matter. For a better understanding, refer to thedetailed description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The specifics of the exclusive rights described herein are particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe embodiments of the invention are apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 depicts an exemplary biosensor according to embodiments of theinvention.

FIGS. 2A-2B depicts another exemplary biosensor according to embodimentsof the invention, in which:

FIG. 2A depicts a cross-sectional side view of the exemplary biosensor,and

FIG. 2B depicts a top down view of the exemplary biosensor.

FIGS. 3A-3L depict an exemplary biosensor after various fabricationoperations according to embodiments of the invention, in which:

FIG. 3A illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3B illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3C illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3D illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3E illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3F illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3G illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3H illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3I illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3J illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3K illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 3L illustrates the exemplary biosensor after a fabricationoperation according to embodiments of the invention;

FIG. 4 depicts an exemplary biosensor according to embodiments of theinvention.

FIG. 5 depicts another exemplary biosensor according to embodiments ofthe invention.

FIG. 6 depicts a flow diagram illustrating a method according to one ormore embodiments of the invention.

FIG. 7 depicts a flow diagram illustrating a method according to one ormore embodiments of the invention.

FIG. 8 depicts a computer system according to one or more embodiments ofthe invention.

The diagrams depicted herein are illustrative. There can be manyvariations to the diagram or the operations described therein withoutdeparting from the spirit of the invention. For instance, the actionscan be performed in a differing order or actions can be added, deletedor modified. Also, the term “coupled” and variations thereof describeshaving a communications path between two elements and does not imply adirect connection between the elements with no interveningelements/connections between them. All of these variations areconsidered a part of the specification.

In the accompanying figures and following detailed description of thedescribed embodiments, the various elements illustrated in the figuresare provided with two or three digit reference numbers. With minorexceptions, the leftmost digit(s) of each reference number correspond tothe figure in which its element is first illustrated.

DETAILED DESCRIPTION

For the sake of brevity, conventional techniques related tosemiconductor device and integrated circuit (IC) fabrication may or maynot be described in detail herein. Moreover, the various tasks andprocess steps described herein can be incorporated into a morecomprehensive procedure or process having additional steps orfunctionality not described in detail herein. In particular, varioussteps in the manufacture of semiconductor devices andsemiconductor-based ICs are well known and so, in the interest ofbrevity, many conventional steps will only be mentioned briefly hereinor will be omitted entirely without providing the well-known processdetails.

Turning now to an overview of technologies that are more specificallyrelevant to aspects of the invention, biosensors can play an importantrole in the characterization of a variety of different biomolecules. Inneuroscience applications, for example, bio sensors of different typescan be used to detect neurotransmitter function or to assess andinvestigate abnormalities.

Several neurodegenerative diseases are associated with abnormalneurotransmitter function. For example, Parkinson's disease can resultfrom a loss of dopamine secreting cells, and a resultant decrease ofdopamine, in the substantia nigra area of the brain. Anotherneurotransmitter, glutamate (or glutamic acid), is associated with andcan play a key role in a number of neurological disorders, includingischemia, schizophrenia, epilepsy, Alzheimer's disease (AD), andParkinson's disease (PD). Abnormal levels of neurotransmitters, oraccumulation of neurotransmitters in particular regions, can signalabnormal function. Glutamate and other neurotransmitters, such asdopamine, can send signals in the brain and throughout the body. In thecase of brain injury or neurological disorders, for instance, glutamatecan accumulate outside of cells due to errors in glutamate transport orimpaired glutamate uptake.

Thus, neurotransmitter identity and location can provide importantinformation for the identification and characterization of a variety ofconditions. In addition, such information can provide valuableinformation for treatment of neurological disorders and illnessesbecause, for example, some of the primary medications used to treat suchconditions seek to change the effects of one or more transmitters, suchas dopamine.

Sensing of particular neurotransmitters can be accomplished in a varietyof ways, depending on the molecule and associated properties inquestion. Biosensors can be categorized by type, for example, such ascalorimetric biosensors, potentiometric biosensors, acoustic wavebiosensors, resistivity biosensors, amperometric biosensors, and opticalbiosensors.

The use and selection of biosensor type can depend, for example, uponthe method of metabolism of the neurotransmitter of interest.Enzymatically controlled neurotransmitter metabolism can in some casesbe investigated by enzyme-based amperometric sensors. Enzyme-basedamperometric sensors can include an enzyme with specificity toward adesired analyte embedded in a polymer on an electrode. Such sensors canbe formed, for example, by electropolymerization of the enzyme andsubstrate around an electrode, such as a metal electrode. Afterpolymerization and prior to use, the substrate can be removed from thesensor providing an available binding site for substrate detection invivo.

Such amperometric sensors are known and can rely, for example, uponelectron generation through enzymatic oxidation of the analyte on theelectrode, which can result in measurable current. Glutamate metabolism,for example, is enzymatically controlled and can have an electricalcurrent in decomposition, through the release of electrons that are inproportion to its concentration. Related measurements can beaccomplished, for example by embedding glutamate oxidase enzyme in aconformal polymer grown on a metal electrode. In such implementations,electrical current can be used to determine concentration ofenzymatically metabolized analytes.

Non-enzymatically controlled neurotransmitters can be measured withresistivity-based methods. Dopamine metabolism, for instance, can bemeasured without enzymatic binding. Dopamine and other non-enzymaticallycontrolled neurotransmitters can be detected and measured, for example,by taking resistivity measurements from an organic electrode imprintedwith the target neurotransmitter. By electropolymerizing a polymericsubstrate with the desired analyte, and then removing the analyte fromthe imprinted substrate, a receptor cavity complimentary to the analytecan be generated in a molecularly imprinted polymer (MIP). Suchresistivity sensors are known and can rely upon, for example, resistancechanges in an unbound versus an analyte-bound sensor. The measuredresistivity in such implementations can be proportional to theconcentration of the target analyte.

Conventional biosensors that can detect or measure a singleneurotransmitter provide only a limited view of neurological processesand conditions. For example, a plurality of neurotransmitters can eachplay a distinct and simultaneous role in neurological impairments.Measurement of multiple neurotransmitters can require the use ofmultiple sensing systems, which can be cumbersome, cost-prohibitive, andcould preclude time-sensitive or time-dependent measurements of multipleanalytes or measurement of multiple analytes in the same region.

In addition, although some neurotransmitter activity occurs on themicron and sub-micron scale, conventional biosensors can lack precisionneeded to measure activity at that scale. Conventional biosensors thatcan only measure on the scale of five to ten microns, for example,cannot detect or sense neurotransmitters across the surface of a singleneuron, which measurements call for nanometer scale resolution.

Aspects of the invention address the above-described shortcomings of theprior art by providing a single device that can simultaneously measuremultiple biomolecules in the same region. In some embodiments, multipletypes of biosensors are included in a single device. Embodiments of theinvention include biosensors capable of nanoscale resolution for sensingneurotransmitters. Embodiments of the invention can include a largearray of nanopillars, wherein each nanopillar can be selectively wiredto allow distinct measurement from each pillar. Each pillar can beformed or treated such that it is selective to a singleneurotransmitter. Embodiments of the invention include a plurality ofnanopillars formed of a conductive metal, such as gold or platinum,wherein each nanopillar can be selectively coated with an organicpolymer that is sensitive to a particular target molecule. In someembodiments of the invention, horizontal organic electrodes associatedwith one or more nanopillars can, by measuring resistivity, detectand/or characterize specific biomolecules. In some embodiments of theinvention, a sensor includes one or more sensors, such as horizontalorganic electrodes, for non-enzymatic neurotransmitter detection and/orcharacterization and one or more sensors for enzymatic neurotransmitterdetection and/or characterization. In some embodiments of the invention,electrically functional nano-pillar electrodes are created across aportion of a device substrate including structures of conductive polymerbetween two or more electrodes. The conductive polymer can includeembedded molecular recognition sites. In some embodiments of theinvention a biosensor for multi-analyte detection is implanted into aneural tissue region. Embodiments of the invention can providebiomolecule concentration over time and for a specific biomolecule type.

Turning now to a more detailed description of aspects of the presentinvention, FIG. 1 depicts an exemplary structure 100 for multi-analytecharacterization according to embodiments of the invention. Theexemplary structure 100 can include a first sensing region 110 and asecond sensing region 120. The first sensing region 110 and secondsensing region 120 can include biosensors for detecting differentanalytes. For example, in an exemplary embodiment of the invention, afirst sensing region 110 detects and measures a first neurotransmitter,such as dopamine, and a second sensing 120 region detects and measures asecond neurotransmitter, such as glutamate. The sensing regions 110, 120can be connected to a processor 106 through an interface layer 108. Theprocessor is in connection with an energy supply layer 104, such as alayer including a battery or capacitor, and a communications interface102, such as a graphical user interface.

Although FIG. 1 depicts two sensing regions, it is understood that thenumber of sensing regions is not limited to two and can vary dependingupon the number and types of analytes to be measured. For example, someembodiments of the invention can include tens or hundreds of sensingregions.

Neurotransmitters and other analytes that can be detected or measuredaccording to embodiment of the invention include any analyte suitablefor the detection methods herein.

Analytes that can be detected with resistivity sensors can includeanalytes that can be imprinted into a polymer matrix with suitableselectivity and that can experience a change in resistivity upon analytebinding. Such analytes can include, but are not limited to, dopamine,epinephrine, ascorbic acid, and uric acid.

Analytes that can be detected with amperometric sensors can includeanalytes that have associated enzymes that are amenable to matriximmobilization without a loss in functionality and that can effect achange in current, for instance through oxidization of the analyte. Forexample, suitable enzymes for amperometric sensors can include, but arenot limited to, glutamate oxidase, lactate oxidase, glucose oxidase, andcholine oxidase. Enzymes for amperometric sensors can be selected basedupon the desired analyte. Exemplary analytes that can be sensed withamperometric sensors can include, but are not limited to, glutamate,lactate, glucose, choline, adenosine, and gamma-amino-butyric acid(GABA).

Biosensors according to embodiments of the invention can includeamperometric sensors and/or resistivity sensors. In some embodiments ofthe invention, the structure includes a plurality of amperometricsensors. In some embodiments of the invention, the structure includes aplurality of resistivity sensors. In some embodiments of the invention,the structure includes both amperometric and resistivity sensors.

In some embodiments of the invention a structure includes a plurality ofamperometric sensors, wherein each of the plurality of amperometricsensors detects the same analyte. In some embodiments of the invention,a system includes different types of amperometric sensors, in whichdifferent sensors are capable of sensing distinct analytes. In someembodiments of the invention a structure includes a plurality ofamperometric sensors that detect two or more different analytes.

In some embodiments of the invention a structure includes a plurality ofresistivity sensors, wherein each of the plurality of resistivitysensors detects the same analyte. In some embodiments of the invention,a system includes different types of resistivity sensors, in whichdifferent sensors are capable of sensing distinct analytes. In someembodiments of the invention a structure includes a plurality ofresistivity sensors that detect two or more different analytes.

FIGS. 2A and 2B depict another exemplary structure 200 for multi-analytecharacterization according to one or more embodiments of the presentinvention in which FIG. 2A is a cross-sectional side view of thestructure 200 and FIG. 2B is a top-down view of the structure of FIG.2A. The structure 200 can include a sensing layer 202. The sensing layer202 can include multiple types of chemical sensors 206, 208, 210,dispersed upon an interface layer 108. The chemical sensors 206, 208,210 can be in any pattern and any number and can be tailored to thedesired application. In some embodiments of the invention, the sensinglayer can include more than two different types of chemical sensors. Forexample, in some embodiments of the invention, the sensing layer caninclude three different types of sensors (as shown in FIG. 2B) or, forexample, twenty different types of sensors (not shown). The chemicalsensors 206, 208, 210 can be formed upon one or more nanopillars and caninclude a single nanopillar structure or multiple nanopillar structures(not shown in FIGS. 2A and 2B). The chemical sensors can be spaced at adistance tailored to the desired application. In some embodiments of theinvention, the chemical sensors 206, 208, 210 are spaced apart from oneanother at a distance of about 200 nanometers (nm) to about 2 microns.

As is shown in FIG. 2B, the structure 200 can include a microfluidicstructure 204 surrounding the chemical sensors 206, 208, 210. In someembodiments of the invention, the microfluidic structure 204 is incontact with some or all of the chemical sensors. The structure 200 canalso include a processor 106 in communication with the sensing region202 through an interface layer 108. The processor is in connection withan energy supply layer 104, such as a layer including a battery orcapacitor, and a communications interface 102, such as a graphical userinterface.

FIGS. 3A-3L depict an exemplary method of fabricating a sensor accordingto one or more embodiments of the present invention.

FIG. 3A depicts a cross sectional side view of an exemplary structure300 after formation of a substrate 308 including a plurality ofnanopillars 302. The nanopillars 302 can each have a base 306 and apillar portion 304. The nanopillars 302 can be formed on the substrateby depositing a resist layer, such as an organic planarization layer(OPL) (not shown in FIG. 3A) on the substrate 308, patterning holes inthe resist layer with known lithography techniques, and plating metalonto the structure 300 in the holes in the resist layer. After platingthe metal of the nanopillars 302, the resist layer can be removed fromthe structure. It is understood that although the exemplary structuredepicts three rows of nanopillars 302, the number of nanopillars canvary and can be tailored to the desired application. For example, insome embodiments of the invention a structure can include tens orhundreds of rows of nanopillars 302.

In some embodiments of the invention, the nanopillars are spaced apartat a pitch of about 200 nm to about 600 nm, such as about 200 nm toabout 500 nm, or about 200 nm to about 400 nm, or about 200 nm to about300 nm. In some embodiments of the invention, the nanopillars can have aheight of about 100 nm to about 1000 nm, such as about 500 nm to about800 nm. In some embodiments of the invention, the nanopillars can have adiameter of about 50 nm to about 100 nm.

FIG. 3B depicts a top down view of the exemplary structure 300 depictedin FIG. 3A showing an exemplary ordered arrangement of nanopillars 302formed on a substrate 308. In other embodiments of the invention, notshown in FIG. 3B, unordered or irregularly spaced nanopillars 302 can beformed on a substrate.

Nanopillars 302 can be formed of conductive metal, such as platinum,gold, silver, nickel, palladium, tin, or copper. In some embodiments ofthe invention, nanopillars 302 include platinum. In some embodiments ofthe invention, nanopillars include copper.

The substrate 308 can include known semiconductor materials, such assilicon (e.g., such as a silicon wafer), silicon germanium, or othersuitable rigid supporting material. Associated wiring (not shown in FIG.3A) can be fabricated using known processes, such as conventional backend of the line technologies.

In some embodiments of the invention, after forming the nanopillars 302,the nanopillars can be lined with an insulating layer 304, as isdepicted in FIG. 3C. The insulating layer can include any knowninsulating material suitable for semiconductor applications, such asaluminum oxide, silicon oxide, or a composite of oxides. The insulatinglayer 304 can be deposited on the structure 300, for instance, by atomiclayer deposition (ALD) using known techniques.

In some embodiments of the invention, after lining the nanopillars withan insulating layer 304, one or more resistivity sensors can be formedon the structure. A resistivity sensor can be fabricated by depositingan OPL layer 309 on the structure 300 and patterning a hard mask layer310 on the OPL layer 309, as is depicted in FIG. 3D. The OPL layer 309can include, for instance, an organic spin-on material. The hardmasklayer 310 can be patterned such to expose one or more nanopillars, suchas two nanopillars, which can function as part of a resistive sensor.The hardmask layer 310 can include, for example, titanium and can have athickness of about 20 nanometers.

After patterning the hardmask layer 310, the unmasked OPL layer 308 canbe etched to expose a portion of insulating layer 304 on one or moreelectrodes 302, as is illustrated in FIG. 3E. In some embodiments of theinvention, not shown in FIG. 3E, the unmasked OPL layer 309 can beetched to expose all of the insulating layer 304 on one or moreelectrodes. Etching the OPL layer 309 can include, for instance,reactive ion etch (RIE). The resulting structure 300 can include one ormore recessed areas for depositing polymeric material.

After recessing the OPL layer 309, the structure can be wet etched, forinstance with dilute HF (DHF), to remove the portion of the insulatinglayer 304 on the electrodes previously exposed through etching the OPLlayer 309, as is illustrated in FIG. 3F. In some embodiments of theinvention, upper portions 303 of a pair of adjacent electrodes 302 areexposed through etching with DHF, as is shown. In some embodiments ofthe invention, more than an upper portion of the electrodes 302, forexample, half of the vertical height or all of the vertical height, isexposed through etching with DHF (not shown in FIG. 3F).

The hard mask layer 310 can be removed from the structure 300 by wetetching, for instance by wet etching with hydrogen peroxide. FIG. 3Gillustrates an exemplary structure 300 after removal of the hard masklayer 310.

After removing the hard mask layer 310, remaining OPL layer 309 can beremoved from the structure 308. For example, OPL layer 309 can bestripped from the structure 300 with plasma treatment, such as O₂ plasmaor N₂/H₂ plasma etching. FIG. 3H depicts an exemplary structure afterremoval of the OPL layer 309. As can be seen in FIG. 3H, a resultantstructure 300 can include adjacent electrodes 312 that are partiallyexposed and partially coated with insulating layer 304 and one or morefully insulated electrodes 314. Partially exposed electrodes 312 canserve as substrates for electro-polymerized material to form resistivitysensors.

To form a resistivity sensor, a memory material 316 can beelectro-polymerized on the partially exposed electrodes 312, as is shownin FIG. 3I. In some embodiments of the invention, voltage is selectivelyapplied to adjacent partially exposed electrodes 312 and the partiallyexposed electrodes 312 are exposed to a conductive porous polymerprecursor containing a desired template molecule (analyte), such asdopamine. Polymer can grow on exposed electrodes with applied voltage.In some embodiments of the invention, multiple locations of a structure300 include pairs of adjacent partially exposed electrodes 312. In someembodiments of the invention, polymerization voltages can be separatelyapplied to different pairs partially exposed electrodes 312 in thepresence of different desired template molecules. Thus, differentlocations of a chip can be fabricated to be selective for differentanalytes.

In some embodiments of the invention, the insulating layer 304 can beremoved from the structure, for instance by stripping with DHF. FIG. 3Jdepicts an exemplary structure 300 after removal of the insulating layer304.

After forming a memory material 316 on the structure 300, the templatemolecules can be removed to generate an imprinted polymer 318, forinstance by washing the memory material or by cycling the voltage ofassociated electrodes to dislodge the template molecules from theconductive porous polymer. FIG. 3K depicts an exemplary structure 300including an imprinted polymer 318 and associated electrodes 312. Theresultant imprinted polymer 318 will have a plurality of cavities, eachhaving a size, shape, and binding affinity (e.g., through hydrophobicinteractions and the like) specific to the template molecule, which canbe the desired analyte.

In some embodiments of the invention, one or more electrodes can befunctionalized along the length of the nanopillar, with differinganalyte sensitivity. In some embodiments of the invention, exposedelectrodes not associated with imprinted polymer 322 can be associatedwith amperometric sensors. For example, in some embodiments of theinvention, a voltage can be selectively applied to one or morenanopillars and the nanopillars exposed to amperometric sensor polymer320. Amperometric sensor polymer 320 can include conductive polymerembedded with an enzyme selective for the desired analyte, such asglutamate oxidase. FIG. 3L depicts an exemplary structure 300 afterformation of an amperometric sensor polymer 320 on a nanopillar. Theamperometric sensor polymer 320 can be electropolymerized with both theenzyme and its substrate (the desired analyte). After polymerization,the substrate can be released from the polymer by washing or by applyingvoltage to the nanopillar sufficient to release the substrate, leavingan amperometric sensor polymer including a plurality of enzymaticbinding sites with affinity to the desired analyte.

Exemplary conductive porous polymers that can be used to generate theimprinted polymer 318 and amperometric sensor polymer 320 can include,for instance, polyaniline with or without miscibility additives,polypyrrole, or poly(3,4-ethylenedioxythiophene) (PEDOT). Suitablemiscibility additives can include, for example, phytic acid, siliconnanoparticles, silicon oxide nanoparticles, carbon nanoparticles,protobacteria proteins, including proteins from the genus Geobacter, andthe like.

FIG. 4 depicts an exemplary biosensor according to embodiments of theinvention. As is shown in FIG. 4, a structure 400 can include both oneor more resistivity sensors 402 and a plurality of amperometric sensors404, and 406. The structure can be selective for a plurality ofanalytes, for instance by including an imprinted polymer 408 selectivefor a first analyte, such as dopamine, a first amperometric sensor 404including a polymer embedded with a first enzyme 410 and a secondamperometric sensor 406 including a polymer embedded with a secondenzyme 412. The exemplary structure 400 includes a substrate 407, suchas a silicon substrate. The imprinted polymer 408 can be formed at anupper portion of the associated nanopillars 414 providing accessiblesurfaces on a top portion 415 and a bottom portion 417 of the imprintedpolymer. Providing an accessible bottom portion 417 of the imprintedpolymer 408 can, for example, provide greater access and surface area todetect analyte and, thereby, could provide greater sensitivity inmeasurement relative, for example, to an imprinted polymer not includingan accessible bottom portion 417.

FIG. 5 depicts another exemplary biosensor according to embodiments ofthe invention. As is shown in FIG. 5, a structure 400 can include bothone or more resistivity sensors 402 and a plurality of amperometricsensors 404, and 406. The structure can be selective for a plurality ofanalytes, for instance by including an imprinted polymer 408 selectivefor a first analyte, such as dopamine, a first amperometric sensor 404including a polymer embedded with a first enzyme 410 and a secondamperometric sensor 406 including a polymer embedded with a secondenzyme 412. The exemplary structure 400 includes a substrate 407, suchas a silicon substrate. As is shown in FIG. 5, a resistivity sensor 408can extend the length of and encompass the associated nanopillars 414.In this embodiment of the invention, the imprinted polymer 408 includesan accessible top portion 415.

FIG. 6 depicts a flow diagram illustrating an exemplary method 600according to one or more embodiments of the invention. The method 600includes, as shown at block 602, forming nanopillars on a substrate. Themethod 600 also includes, as shown at block 604, lining the nanopillarswith an insulating layer to generate a plurality of lined nanopillars.The method 600 also includes, as shown at block 606, removing theinsulating layer from an upper portion of a pair of adjacent nanopillarsto generate exposed adjacent nanopillars. The method 600 also includes,as shown at block 608, forming a resistivity sensor on the exposedadjacent nanopillars. The method 600 also includes, as shown at block610, removing the insulating layer from a lined nanopillar to generatean exposed nanopillar. The method 600 also includes, as shown at block612, forming an amperometric sensor on the exposed nanopillar.

FIG. 7 depicts a flow diagram illustrating an exemplary method 700according to one or more embodiments of the invention. The method 700includes, as shown at block 702, receiving a signal from a multi-analytesensor in contact with a biological tissue. Biological tissue caninclude tissue containing one or more analytes under investigation andcan include, for instance, neuronal tissue and/or brain tissue. Themethod 700 also includes, as shown at block 704, determining aresistivity value from a resistivity sensor. The resistivity value, forexample, can be proportional to the concentration of an analyte. Themethod 700 also includes, as shown at block 706, generating aconcentration of a first analyte based at least in part upon theresistivity value. The method also includes determining an electricalcurrent from an amperometric sensor, as shown at block 708. Theelectrical current, for example, can be proportional to theconcentration of an enzyme-active analyte. The method 700 also includes,as shown at block 710, generating a concentration of a second analytebased at least in part upon the electrical current.

Referring now to FIG. 8, a schematic of a computer system 800 is shownaccording to a non-limiting embodiment. The cloud computer system 800 isonly one example of a suitable computer system and is not intended tosuggest any limitation as to the scope of use or functionality ofembodiments of the invention described herein. Regardless, computersystem 800 is capable of being implemented and/or performing any of thefunctionality set forth hereinabove.

Computer system 800 includes a computer system/server 12, which isoperational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that can besuitable for use with computer system/server 12 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 12 can be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules can includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 12 can be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules can be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 8, computer system/server 12 is shown in the form of ageneral-purpose computing device. The components of computersystem/server 12 can include, but are not limited to, one or moreprocessors or processing units 16, a system memory 28, and a bus 18 thatcouples various system components including system memory 28 toprocessor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media can be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 can further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 can include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,can be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, can include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

Computer system/server 12 can also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.,one or more devices that enable a user to interact with computersystem/server 12, and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Various embodiments of the present invention are described herein withreference to the related drawings. Alternative embodiments can bedevised without departing from the scope of this invention. Althoughvarious connections and positional relationships (e.g., over, below,adjacent, etc.) are set forth between elements in the followingdescription and in the drawings, persons skilled in the art willrecognize that many of the positional relationships described herein areorientation-independent when the described functionality is maintainedeven though the orientation is changed. These connections and/orpositional relationships, unless specified otherwise, can be direct orindirect, and the present invention is not intended to be limiting inthis respect. Accordingly, a coupling of entities can refer to either adirect or an indirect coupling, and a positional relationship betweenentities can be a direct or indirect positional relationship. As anexample of an indirect positional relationship, references in thepresent description to forming layer “A” over layer “B” includesituations in which one or more intermediate layers (e.g., layer “C”) isbetween layer “A” and layer “B” as long as the relevant characteristicsand functionalities of layer “A” and layer “B” are not substantiallychanged by the intermediate layer(s).

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, process, method, article, or apparatus thatcomprises a list of elements is not necessarily limited to only thoseelements but can include other elements not expressly listed or inherentto such composition, mixture, process, method, article, or apparatus.

Additionally, the term “exemplary” is used herein to mean “serving as anexample, instance or illustration.” Any embodiment or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at least one”and “one or more” are understood to include any integer number greaterthan or equal to one, i.e. one, two, three, four, etc. The terms “aplurality” are understood to include any integer number greater than orequal to two, i.e. two, three, four, five, etc. The term “connection”can include an indirect “connection” and a direct “connection.”

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc., indicate that the embodiment describedcan include a particular feature, structure, or characteristic, butevery embodiment may or may not include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

For purposes of the description hereinafter, the terms “upper,” “lower,”“right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” andderivatives thereof shall relate to the described structures andmethods, as oriented in the drawing figures. The terms “overlying,”“atop,” “on top,” “positioned on” or “positioned atop” mean that a firstelement, such as a first structure, is present on a second element, suchas a second structure, wherein intervening elements such as an interfacestructure can be present between the first element and the secondelement. The term “direct contact” means that a first element, such as afirst structure, and a second element, such as a second structure, areconnected without any intermediary conducting, insulating orsemiconductor layers at the interface of the two elements.

The phrase “selective to,” such as, for example, “a first elementselective to a second element,” means that the first element can beetched and the second element can act as an etch stop.

The terms “about,” “substantially,” “approximately,” and variationsthereof, are intended to include the degree of error associated withmeasurement of the particular quantity based upon the equipmentavailable at the time of filing the application. For example, “about”can include a range of ±8% or 5%, or 2% of a given value.

As previously noted herein, for the sake of brevity, conventionaltechniques related to semiconductor device and integrated circuit (IC)fabrication may or may not be described in detail herein. By way ofbackground, however, a more general description of the semiconductordevice fabrication processes that can be utilized in implementing one ormore embodiments of the present invention will now be provided. Althoughspecific fabrication operations used in implementing one or moreembodiments of the present invention can be individually known, thedescribed combination of operations and/or resulting structures of thepresent invention are unique. Thus, the unique combination of theoperations described in connection with the fabrication of asemiconductor device according to the present invention utilize avariety of individually known physical and chemical processes performedon a semiconductor (e.g., silicon) substrate, some of which aredescribed in the immediately following paragraphs.

In general, the various processes used to form a micro-chip that will bepackaged into an IC fall into four general categories, namely, filmdeposition, removal/etching, semiconductor doping andpatterning/lithography. Deposition is any process that grows, coats, orotherwise transfers a material onto the wafer. Available technologiesinclude physical vapor deposition (PVD), chemical vapor deposition(CVD), electrochemical deposition (ECD), molecular beam epitaxy (MBE)and more recently, atomic layer deposition (ALD) among others.Removal/etching is any process that removes material from the wafer.Examples include etch processes (either wet or dry), andchemical-mechanical planarization (CMP), and the like. Semiconductordoping is the modification of electrical properties by doping, forexample, transistor sources and drains, generally by diffusion and/or byion implantation. These doping processes are followed by furnaceannealing or by rapid thermal annealing (RTA). Annealing serves toactivate the implanted dopants. Films of both conductors (e.g.,poly-silicon, aluminum, copper, etc.) and insulators (e.g., variousforms of silicon dioxide, silicon nitride, etc.) are used to connect andisolate transistors and their components. Selective doping of variousregions of the semiconductor substrate allows the conductivity of thesubstrate to be changed with the application of voltage. By creatingstructures of these various components, millions of transistors can bebuilt and wired together to form the complex circuitry of a modernmicroelectronic device. Semiconductor lithography is the formation ofthree-dimensional relief images or patterns on the semiconductorsubstrate for subsequent transfer of the pattern to the substrate. Insemiconductor lithography, the patterns are formed by a light sensitivepolymer called a photo-resist. To build the complex structures that makeup a transistor and the many wires that connect the millions oftransistors of a circuit, lithography and etch pattern transfer stepsare repeated multiple times. Each pattern being printed on the wafer isaligned to the previously formed patterns and slowly the conductors,insulators and selectively doped regions are built up to form the finaldevice.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may includecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instruction by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein includes anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate possibleimplementations of fabrication and/or operation methods according tovarious embodiments of the present invention. Variousfunctions/operations of the method are represented in the flow diagramby blocks. In some alternative implementations, the functions noted inthe blocks can occur out of the order noted in the Figures. For example,two blocks shown in succession can, in fact, be executed substantiallyconcurrently, or the blocks can sometimes be executed in the reverseorder, depending upon the functionality involved.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments described. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdescribed herein.

What is claimed is:
 1. A computer-implemented method of multi-analytedetection, the method comprising: receiving, by a processor, a signalfrom a multi-analyte sensor in contact with a biological tissue, whereinthe multi-analyte sensor comprises a resistivity sensor and anamperometric sensor; determining, by the processor, a resistivity valuefrom the resistivity sensor; generating, by the processor, aconcentration of a first analyte based at least in part upon theresistivity value; determining, by the processor, an electrical currentfrom the amperometric sensor; and generating, by the processor, aconcentration of a second analyte based at least in part upon theelectrical current.
 2. The computer-implemented method of claim 1,wherein the biological tissue comprises neuronal tissue.
 3. Thecomputer-implemented method of claim 1, wherein the first analyte isdopamine.
 4. The computer-implemented method of claim 1, wherein thesecond analyte comprises an enzyme-active neurotransmitter.
 5. Thecomputer-implemented method of claim 4, wherein the amperometric sensoris selective to the enzyme-active neurotransmitter.
 6. Thecomputer-implemented method of claim 5, wherein the enzyme-activeneurotransmitter is selected from the group consisting of glutamate,lactate, glucose, choline, adenosine, and gamma-amino-butyric acid(GABA).
 7. The computer-implemented method of claim 6, wherein theenzyme-active neurotransmitter comprises glutamate.
 8. Thecomputer-implemented method of claim 7, wherein determining theelectrical current comprises measuring the electrical current from adecomposition of Glutimate.
 9. The computer-implemented method of claim1, wherein the amperometric sensor comprises a conductive porouspolymer.
 10. The computer-implemented method of claim 9, wherein theconductive porous polymer comprises a polymer selected from the groupconsisting of polyaniline, polypyrrole,poly(3,4-ethylenedioxythiophene), and mixtures thereof
 11. Thecomputer-implemented method of claim 10, wherein the conductive porouspolymer further comprises a miscibility additive.
 12. Acomputer-implemented method of multi-analyte detection, the methodcomprising: providing a multi-analyte sensor comprising a sensing layerformed on an interface layer, the sensing layer comprising an array ofalternating chemical sensors, the array of alternating chemical sensorscomprising a first sensor type and a second sensor type, wherein thefirst sensor type comprises a resistivity sensor and the second sensortype comprises an amperometric sensor; providing a processorcommunicatively coupled to the multi-analyte sensor; receiving, by theprocessor, a resistivity value from the resistivity sensor; generating,by the processor, a concentration of a first analyte based at least inpart upon the resistivity value; receiving, by the processor, anelectrical current from the amperometric sensor; and generating, by theprocessor, a concentration of a second analyte based at least in partupon the electrical current.
 13. The computer-implemented method ofclaim 12, wherein each of the chemical sensors are formed on a topsurface of a nanopillar.
 14. The computer-implemented method of claim 12further comprising contacting the multi-analyte sensor with a biologicaltissue.
 15. The computer-implemented method of claim 14, wherein thebiological tissue comprises neuronal tissue.
 16. Thecomputer-implemented method of claim 12, wherein the first analyte isdopamine.
 17. The computer-implemented method of claim 12, wherein thesecond analyte comprises an enzyme-active neurotransmitter.
 18. Thecomputer-implemented method of claim 17, wherein the amperometric sensoris selective to the enzyme-active neurotransmitter.
 19. Thecomputer-implemented method of claim 18, wherein the enzyme-activeneurotransmitter is selected from the group consisting of glutamate,lactate, glucose, choline, adenosine, and gamma-amino-butyric acid(GABA).
 20. The computer-implemented method of claim 19, wherein theenzyme-active neurotransmitter comprises glutamate.